Porous LaFeO3 walnuts for efficient visible light driven photocatalytic detoxification of harmful organic pollutants

Abstract

The orthorhombic crystalline walnuts consisting of nanoparticles with an average size of ∼72 nm of stoichiometric LaFeO3 (LFO) offering 10.280 m2/g surface area and band gap of 2.29 eV exhibited the photocatalytic degradation of multiple organic dyes under the Xenon lamp and sunlight. The kinetic study revealed 96.02, 90.22, and 82.45% degradation of Crystal Violet (CV), Methylene Blue (MB), and Rhodamine B (RhB) with a rate constant of 0.012, 0.0096, and 0.0073 min−1, respectively, after continuous irradiation of 240 min. The LFO walnuts delivered sunlight driven degradation of ∼91% for organic CV dye. The scavenger and PL study revealed the active involvement of h+ and O2− in the photocatalytic degradation of dyes. Photocatalytic degradation intermediates were identified using the mass spectroscopy (ESI-LCMS) technique. N-de-methylation of organic dyes during irradiation followed by cleavage of conjugated chromophore structure and opening of the benzene ring in CV; however, oxidation in MB; leads to the formation of ecological compounds along with the CO2 and H2O. Our results propose the LFO walnuts as an excellent candidate for stable and sunlight driven degradation of organic dyes.